Tag Archives: Firecracker

Run isolated sandboxes with full lifecycle control: AWS Lambda introduces MicroVMs

Post Syndicated from Micah Walter original https://aws.amazon.com/blogs/aws/run-isolated-sandboxes-with-full-lifecycle-control-aws-lambda-introduces-microvms/

Today, we are announcing AWS Lambda MicroVMs, a new serverless compute primitive within AWS Lambda that lets you run code generated by users or AI in isolated, stateful execution environments. You get virtual machine level isolation, near-instant launch and resume, and direct control over environment lifecycle and state, all without managing infrastructure or building expertise in complex virtualization technologies. Lambda MicroVMs are powered by Firecracker, the same lightweight virtualization technology that has powered over 15 trillions of monthly Lambda function invocations.

Why customers need this
Over the past few years a new class of multi-tenant applications has emerged that all share the need to hand each end user their own dedicated execution environment in which to safely run code that the application developer did not write. AI coding assistants, interactive code environments, data analytics platforms, vulnerability scanners, and game servers that run user-supplied scripts all fit this pattern. Building that capability today means making a difficult choice. Virtual machines deliver strong isolation but take minutes to start. Containers launch in seconds, yet their shared-kernel architecture requires significant custom hardening to safely contain untrusted code. Functions as a service are optimized for event-driven, request-response workloads, but are not designed for long-running interactive sessions that need to retain environment state across user interactions. That leaves developers either accepting tradeoffs between performance and isolation, or investing significant engineering resources to build and operate custom virtualization infrastructure to achieve isolated execution while delivering low-latency experiences to end-users. This presents an effort that demands deep expertise and pulls engineering time away from the product they are actually trying to build.

Lambda MicroVMs is purpose-built for exactly this gap. Each MicroVM gives a single end user or session its own isolated environment that launches rapidly, retains memory and disk state for the length of the session, and pauses to a low idle cost when the user steps away. Because the same Firecracker technology already underpins AWS Lambda Functions, you inherit the operational maturity of a service that has been running this stack at scale.

Let’s try it out
To get started, I navigated to the AWS Lambda console, where Lambda MicroVMs now appears in the left-hand navigation menu. I first need to create a MicroVM Image.

I packaged a Flask web app and its Dockerfile into a zip file, uploaded it to an Amazon Simple Storage Service (Amazon S3) bucket.

My Flask API – app.py

import logging

from flask import Flask, jsonify

app = Flask(__name__)
logging.basicConfig(level=logging.INFO)


@app.route("/")
def hello():
    app.logger.info("Received request to hello world endpoint")
    return jsonify(message="Hello, World!")


if __name__ == "__main__":
    app.run(host="0.0.0.0", port=5000)

My Dockerfile


FROM public.ecr.aws/lambda/microvms:al2023-minimal
RUN dnf install -y python3 python3-pip && dnf clean all

WORKDIR /app

COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

COPY app.py .

EXPOSE 5000

CMD ["gunicorn", "--bind", "0.0.0.0:5000", "app:app"]

I used the following command to create my MicroVM Image.

aws lambda-microvms create-microvm-image \
--code-artifact uri=<path/to/s3/artifact.zip> --name <VM_image_name> \
--base-image-arn arn:aws:lambda:us-east-1:aws:microvm-image:al2023-1 \
--build-role-arn <IAM role ARN>

You can also create the MicroVM Image in the AWS Console as in the image above. Once I ran the command, Lambda retrieved the zip, ran the Dockerfile, initialized the application, and took a Firecracker snapshot of the running disk and memory state. Build logs streamed in real time to Amazon CloudWatch under /aws/lambda/microvms/<image-name>, and when the image was ready it appeared in the console with its Amazon Resource Name (ARN) and version number.

aws lambda-microvms run-microvm \
--image-identifier arn:aws:lambda:<region>:<acct>:microvm-image:my-image \
--execution-role-arn arn:aws:iam::<acct>:role/MicroVMExecutionRole \
--idle-policy '{"maxIdleDurationSeconds":900,"suspendedDurationSeconds":300,"autoResumeEnabled":true}'

Launching can also be done via the AWS Console or the CLI. I passed the image ARN and an idle policy configured to auto-suspend after 15 minutes of inactivity and auto-resume on the next incoming request. No networking setup was required. Lambda assigned the MicroVM a unique ID, returned a dedicated endpoint URL, and started a new MicroVM with my Flask app already running, since it was resumed from a snapshot. My Flask app was already running the moment the launch completed. One API call to get a fully initialized, bootstrapped compute environment.

To send traffic, I generated a short-lived auth token with the CLI and attached it to a plain HTTPS request using the X-aws-proxy-auth header. The request landed on my Flask app immediately. I then let the MicroVM sit idle past the suspend threshold, at which point the MicroVM was suspended, with its memory and disk state snapshotted and stored. I then sent another request, and it resumed with the application state fully intact. From the client side, the pause never happened.

How it works
Under the covers, Lambda MicroVMs delivers three capabilities that, until today, no single AWS compute service offered together. The first is virtual machine level isolation, which comes from Firecracker. Each session runs in its own dedicated MicroVM with no shared kernel and no shared resources between users, so untrusted code supplied by one user is contained to their execution environment, without access to other environments or the underlying system. The second is rapid launch and resume. The model is image-then-launch: you create a MicroVM Image by supplying a Dockerfile and code packaged as a zip artifact in Amazon S3, and Lambda runs your Dockerfile, initializes your application, and takes a Firecracker snapshot of the running environment’s memory and disk state. Every subsequent MicroVM launched from that image resumes from the pre-initialized snapshot rather than booting cold, which means launches and idle resumes both achieve near-instant startup latency. Even a multi-gigabyte interactive session comes back online quickly enough to feel responsive to the end user. The third is stateful execution. A running MicroVM retains memory, disk, and running processes across the user’s session. During idle periods, a MicroVM can be suspended – with memory and disk state intact – and resumed when traffic arrives. Installed packages, loaded models, and working filesets are readily available when the user resumes their session. MicroVMs support up to 8 hours of total runtime and can be suspended automatically after a configurable idle window, which makes it straightforward to build products as varied as software vulnerability scans that complete in minutes, data analytics applications that run for hours, and interactive coding sessions with extended idle periods. As Lambda MicroVMs are started from pre-initialized snapshots, applications generating unique content, establishing network connections, or loading ephemeral data during initialization may need to integrate with service-provided hooks for compatibility.

Lambda MicroVMs is a new resource within AWS Lambda, with a distinct API surface. Lambda Functions remain the right choice for event-driven, request-response workloads, and Lambda MicroVMs is purpose-built for multi-tenant applications that need to hand each end user or session their own isolated environment to execute user- or AI-generated code. The two complement each other. An application using Lambda Functions for its event-driven backbone can call into Lambda MicroVMs for the steps that need to run untrusted code in isolation. You bring the application, and the service delivers the execution environment.

Now available
AWS Lambda MicroVMs is available today in the US East (N. Virginia, Ohio), US West (Oregon), Europe (Ireland) and Asia Pacific (Tokyo) Regions, on the ARM64 architecture, with up to 16 vCPUs, 32 GB of memory, and 32 GB of disk per MicroVM. Idle MicroVMs can be suspended explicitly through an API call or automatically through a lifecycle policy, which reduces the running cost while preserving full state for fast resume. Pricing details can be found on the AWS Lambda pricing page.

To get started, visit the AWS Lambda console, or learn more on the Lambda MicroVMs product page. For documentation, see the Lambda MicroVMs Developer Guide.

Optimizing Lambda functions packaged as container images

Post Syndicated from Rob Sutter original https://aws.amazon.com/blogs/compute/optimizing-lambda-functions-packaged-as-container-images/

AWS Lambda launched support for packaging and deploying functions as container images at re:Invent 2020. In this post you learn how to build container images that reduce image size as well as build, deployment, and update time. Lambda container images have unique characteristics to consider for optimization. This means that the techniques you use to optimize container images for Lambda functions are slightly different from those you use for other environments.

To understand how to optimize container images, it helps to understand how container images are packaged, as well as how the Lambda service retrieves, caches, deploys, and retires container images.

Pre-requisites and assumptions

This post assumes you have access to an IAM user or role in an AWS account and a version of the tar utility on your machine. You must also install Docker and the AWS SAM CLI and start Docker.

Lambda container image packaging

Lambda container images are packaged according to the Open Container Initiative (OCI) Image Format specification. The specification defines how programs build and package individual layers into a single container image. To explore an example of the OCI Image Format, open a terminal and perform the following steps:

  1. Create an AWS SAM application.
    sam init –name container-images
  2. Choose 1 to select an AWS quick start template, then choose 2 to select container image as the packaging format, and finally choose 9 to use the amazon-go1.x-base image.
    Image showing the suggested choices for a sam init command
  3. After the AWS SAM CLI generates the application, enter the following commands to change into the new directory and build the Lambda container image
    cd container-images
    sam build
  4. AWS SAM builds your function and packages it as helloworldfunction:go1.x-v1. Export this container image to a tar archive and extract the filesystem into a new directory to explore the image format.
    docker save helloworldfunction:go1.x-v1 &gt; oci-image.tar
    mkdir -p image
    tar xf oci-image.tar -C image

The image directory contains several subdirectories, a container metadata JSON file, a manifest JSON file, and a repositories JSON file. Each subdirectory represents a single layer, and contains a version file, its own metadata JSON file, and a tar archive of the files that make up the layer.

Image of the result of running the tree command in a terminal window

The manifest.json file contains a single JSON object with the name of the container metadata file, a list of repository tags, and a list of included layers. The list of included layers is ordered according to the build order in your Dockerfile. The metadata JSON file in each subfolder also contains a mapping from each layer to its parent layer or final container.

Your function should have layers similar to the following. A separate layer is created any time files are added to the container image. This includes FROM, RUN, ADD, and COPY statements in your Dockerfile and base image Dockerfiles. Note that the specific layer IDs, layer sizes, number, and composition of layers may change over time.

ID Size Description Your function’s Dockerfile step
5fc256be… 641 MB Amazon Linux
c73e7f67… 320 KB Third-party licenses
de5f5100… 12 KB Lambda entrypoint script
2bd3c722… 7.8 MB AWS Lambda RIE
5d9d381b… 10.0 MB AWS Lambda runtime
cb832ffc… 12 KB Bootstrap link
1fcc74e8… 560 KB Lambda runtime library FROM public.ecr.aws/lambda/go:1
acb8dall… 9.6 MB Function code COPY –from=build-image /go/bin/ /var/task/

Runtimes generate a filesystem image by destructively overlaying each image layer over its parent. This means that any changes to one layer require all child layers to be recreated. In the following example, if you change the layer cb832ffc... then the layers 1fcc74e8… and acb8da111… are also considered “dirty” and must be recreated from the new parent image. This results in a new container image with eight layers, the first five the same as the original image, and the last three newly built, each with new IDs and parents.

Representation of a container image with eight layers, one of which is updated requiring two additional child layers to be updated also.

The layered structure of container images informs several decisions you make when optimizing your container images.

Strategies for optimizing container images

There are four main strategies for optimizing your container images. First, wherever possible, use the AWS-provided base images as a starting point for your container images. Second, use multi-stage builds to avoid adding unnecessary layers and files to your final image. Third, order the operations in your Dockerfile from most stable to most frequently changing. Fourth, if your application uses one or more large layers across all of your functions, store all of your functions in a single repository.

Use AWS-provided base images

If you have experience packaging traditional applications for container runtimes, using AWS-provided base images may seem counterintuitive. The AWS-provided base images are typically larger than other minimal container base images. For example, the AWS-provided base image for the Go runtime public.ecr.aws/lambda/go:1 is 670 MB, while alpine:latest, a popular starting point for building minimal container images, is only 5.58 MB. However, using the AWS-provided base images offers three advantages.

First, the AWS-provided base images are cached pro-actively by the Lambda service. This means that the base image is either nearby in another upstream cache or already in the worker instance cache. Despite being much larger, the deployment time may still be shorter when compared to third-party base images, which may not be cached. For additional details on how the Lambda service caches container images, see the re:Invent 2021 talk Deep dive into AWS Lambda security: Function isolation.

Second, the AWS-provided base images are stable. As the base image is at the bottom layer of the container image, any changes require every other layer to be rebuilt and redeployed. Fewer changes to your base image mean fewer rebuilds and redeployments, which can reduce build cost.

Finally, the AWS-provided base images are built on Amazon Linux and Amazon Linux 2. Depending on your chosen runtime, they may already contain a number of utilities and libraries that your functions may need. This means that you do not need to add them in later, saving you from creating additional layers that can cause more build steps leading to increased costs.

Use multi-stage builds

Multi-stage builds allow you to build your code in larger preliminary images, copy only the artifacts you need into your final container image, and discard the preliminary build steps. This means you can run any arbitrarily large number of commands and add or copy files into the intermediate image, but still only create one additional layer in your container image for the artifact. This reduces both the final size and the attack surface of your container image by excluding build-time dependencies from your runtime image.

AWS SAM CLI generates Dockerfiles that use multi-stage builds.

FROM golang:1.14 as build-image
WORKDIR /go/src
COPY go.mod main.go ./
RUN go build -o ../bin

FROM public.ecr.aws/lambda/go:1
COPY --from=build-image /go/bin/ /var/task/

# Command can be overwritten by providing a different command in the template directly.
CMD ["hello-world"]

This Dockerfile defines a two-stage build. First, it pulls the golang:1.14 container image and names it build-image. Naming intermediate stages is optional, but it makes it easier to refer to previous stages when packaging your final container image. Note that the golang:1.14 image is 810 MB, is not likely to be cached by the Lambda service, and contains a number of build tools that you should not include in your production images. The build-image stage then builds your function and saves it in /go/bin.

The second and final stage begins from the public.ecr.aws/lambda/go:1 base image. This image is 670 MB, but because it is an AWS-provided image, it is more likely to be cached on worker instances. The COPY command copies the contents of /go/bin from the build-image stage into /var/task in the container image, and discards the intermediate stage.

Build from stable to frequently changing

Any time a layer in an image changes, all layers that follow must be rebuilt, repackaged, redeployed, and recached by the Lambda service. In practice, this means that you should make your most frequently occurring changes as late in your Dockerfile as possible.

For example, if you have a stable Lambda function that uses a frequently updated machine learning model to make predictions, add your function to the container image before adding the machine learning model. However, if you have a function that changes frequently but relies on a stable Lambda extension, copy the extension into the image first.

If you put the frequently changing component early in your Dockerfile, all the build steps that follow must be re-run every time that component changes. If one of those actions is costly, for example, compiling a large library or running a complex simulation, these repetitions add unnecessary time and cost to your deployment pipeline.

Use a single repository for functions with large layers

When you create an application with multiple Lambda functions, you either store the container images in a single Amazon ECR repository or in multiple repositories, one for each function. If your application uses one or more large layers across all of your functions, store all of your functions in a single repository.

ECR repositories compare each layer of a container image when it is pushed to avoid uploading and storing duplicates. If each function in your application uses the same large layer, such as a custom runtime or machine learning model, that layer is stored exactly once in a shared repository. If you use a separate repository for each function, that layer is duplicated across repositories and must be uploaded separately to each one. This costs you time and network bandwidth.

Conclusion

Packaging your Lambda functions as container images enables you to use familiar tooling and take advantage of larger deployment limits. In this post you learn how to build container images that reduce image size as well as build, deployment, and update time. You learn some of the unique characteristics of Lambda container images that impact optimization. Finally, you learn how to think differently about image optimization for Lambda functions when compared to packaging traditional applications for container runtimes.

For more information on how to build serverless applications, including source code, blogs, videos, and more, visit the Serverless Land website.